This invention relates to a feeder assembly for highly viscous particulate material.
In the processing of highly viscous particulate material such as saw dust, brown sugar, ground hard candy and cookie mixes wherein the cookie particles are coated with oil, frequently the viscous particulate material is temporarily stored in a hopper prior to conveyance to a processing station. Because these materials have a high degree of surface stickiness, the material in the hopper tends to adhere to the sides of the hopper, whereby tunnels are formed in the hopper supply.
Many feeder assemblies for the transport of viscous materials have been disclosed, which feeder assemblies include counterrotating rolls or gears disposed at the bottom of a hopper or reservoir for forcing viscous material from the hopper out through an outlet at the bottom of the hopper. For example, U.S. Pat. No. 4,137,023 to Moked et al. is directed to an apparatus for the recovery, compounding and fabricating of plastic material, the apparatus including a gear pump disposed at the bottom of a gear housing in juxtaposition to an outlet thereof. The gears are driven so that portions thereof located at a meshing zone above the gear housing outlet move away from the outlet. Moked et al. is directed in particular to the provision of sealing inserts at the outlet for engaging the teeth of the gears to improve pump efficiencies. In U.S. Pat. No. 2,814,216 to Meagher et al., a pair of counterrotating rolls are disposed near the outlet end of a hopper, the portions of the rolls at the nip therebetween moving downwardly towards the outlet of the hopper. Like Moked et al., U.S. Pat. Nos. 2,698,962, 2,019,202 and 1,699,417 all disclose feeding apparatus for viscous materials wherein the apparatus includes counterrotating rolls or gears having directions of rotation such that portions of the rolls or gears at a meshing zone or nip of the rotating members move away from a hopper outlet.
Further devices for use in processing highly viscous materials have been proposed, which devices include two pairs of counterrotating rollers juxtaposed to one another. U.S. Pat. No. 3,632,091 to Ford exemplarily discloses a machine for preparing plasticized thermoplastics material by passing a plastic strip through a nip between a first pair of counterrotating rolls below which rolls is disposed a second pair of counterrotating rolls. The rolls define respective nips located above one another and above an outlet to a roll housing. The rolls all rotate downwardly towards the outlet at the nips of the rolls.
U.S. Pat. Nos. 2,092,720 to Urquhart and 2,078,777 to Schade are directed to rubber or plastics processing machines each having two pairs of counterrotating rolls, the lower pair rotating upwardly at a common nip and the upper rolls rotating downwardly at a common nip. U.S. Pat. No. 2,693,879 to Gahrman discloses a similar configuration of rolls for transporting solids into or from a gas or liquid.
None of the above-described patents is directed in particular to the transport of highly viscous particulate material. Accordingly, none of the discloses devices appears to be especially effective in the feeding of such material.
An object of the present invention is to provide an improved feeder assembly especially adapted for feeding highly viscous particulate material.
Another object of the present invention is to provide such an assembly with a hopper for holding the particulate material, wherein the formation of tumnels in the contained material is eliminated.
Yet another object of the present invention is to provide such an assembly in which improved agitators are disposed in the hopper.